Karl
Brown, pioneer of linear accelerators to treat
cancer, dies

Karl
Leslie Brown, professor emeritus of applied research
at the Stanford Linear Accelerator Center (SLAC) and
pioneer in the development of linear accelerators for
cancer treatment, died of heart failure Aug. 29 at
Stanford Hospital. He was 76.

"Karl
has made innumerable contributions in many areas to
the work of the Hansen Laboratories on the main
campus and to SLAC," said SLAC Director Emeritus
Wolfgang K. H. Panofsky, a longtime friend and
colleague. "He is probably best known
internationally for his development of the programs
which make it possible to easily trace the path of
particles through complex magnetic beam transport
systems. However, his contributions go well beyond
that and we all are extremely sad about his
passing."

Brown
was born in Coalville, Utah, on Sept. 30, 1925. His
father was a carpenter and part-time farmer, and his
mother, a nurse. He attended the University of Utah
as an electrical engineering student but in 1946
transferred to Stanford as a senior to work on
particle accelerators. This move was the beginning of
a Stanford career spanning more than half a century.

He
earned B.S. ('47), M.S. ('49) and Ph.D. ('53) degrees
in physics from Stanford and served at SLAC as a
senior research associate from 1962 to 1974, adjunct
professor from 1974 to 1982 and professor since 1983.
SLAC has a program to award employees for each decade
of service, and Brown was the first recipient of a
"50 Year Award." He remained professionally
active until his death.

"When
I arrived at Stanford University in 1951,"
Panofsky recalled, "Karl was already there
working with Drs. Edward Ginzton and Marvin Chodorow
on klystrons [devices that generate and amplify the
high-frequency electromagnetic waves required for
particle accelerators] and the then nascent Mark III
linear accelerator. We have been friends and
colleagues ever since." Brown's commissioning of
the preceding Mark II accelerator qualified him for
his physics doctorate.

Declining
offers from prestigious East Coast institutions,
Brown decided to pursue his research at Stanford and
in 1953 joined the Physics Department's Hansen
Laboratories. In the early 1960s, when Panofsky
conceived the idea for the Stanford linear
accelerator, Brown became a member of the core team
of young scientists who designed and built the
2-mile-long accelerator under Panofsky's direction.

In 1958,
Brown was the first to use matrix algebra to
calculate magnetic-optical aberrations in charged
particle spectrometers, used by physicists for the
precise analysis of nuclear and subnuclear structure.
He developed a computer code called TRANSPORT to
facilitate the equipment design process. This code
later became a tool used worldwide to design
spectrometers, beam lines and accelerators ranging in
energies up to 1 million million electron-volts (1
TeV).

Explained
SLAC experimental physicist Vera Lüth, Brown's wife
of 25 years: "His main contribution was to
develop the scientific and mathematical concepts for
magnetic-optical systems for charged particle
transport and to make them widely accessible for
practical use by scientists and engineers."

Brown
also introduced the use of sextupole magnets (those
having six poles) to enhance the performance of
spectrometers in SLAC's End Station, at the terminus
of the linear accelerator, where scientists conducted
experiments with high-energy electrons hitting
stationary atoms. While scientists were colliding
beams in circular machines, Brown in the 1960s
proposed having two linear accelerators shoot beams
at each other. That informal suggestion is now the
basis of advanced accelerator planning.

Brown
later designed achromatic magnetic optical systems.
Such systems can bend beams by the same amount to a
very good approximation independent of their
energies. His designs made it possible to engineer
beams as small as a millionth of a meter (i.e., one
micron). They found application in medical diagnosis
and treatment, and modifications of his designs are
widely used.

Brown's
beam work even attracted military interest because of
its relevance to Reagan's Star Wars system, Lüth
said, and he taught some classes to military
scientists. His publication list is relatively short,
but it greatly influenced designers of accelerators.
Traveling worldwide to assist in design of
spectrometers and accelerators, Brown took
sabbaticals in 1959 at Orsay in France, from 1972 to
1973 at the European Laboratory for Particle Physics
(CERN) and from 1992 to 1994 at the since abandoned
Superconducting Super Collider in Texas.

Small
linear accelerators to treat cancer

Though
Brown was internationally renowned as an expert in
beam optics for nuclear spectrometers and high-energy
particle accelerators, his greatest satisfaction came
from his contributions toward the development of
small linear accelerators for radiation therapy. As a
graduate student in the 1950s, he was part of a small
research team at Stanford that, with applied physics
graduate students Arnold Eldredge and Ken Mallory and
faculty members Edward Ginzton of the Physics
Department and Henry S. Kaplan of the Medical School,
designed the first linear accelerator in the United
States to be used successfully to treat a cancer
patient.

In the
late 1960s, Brown initiated and led the development
by Varian Associates of the first commercially
successful line of such machines, the CLINAC series.
The present-day incarnation of CLINAC treats more
than 100,000 patients a day worldwide. Brown was
president and chief scientist of Spectromagnetics, an
accelerator magnet design and manufacturing company
that was sold to Varian Associates in 1966. During a
hiatus from Stanford from 1966 to 1968, he served at
Varian's Radiation Division as senior scientist and
director of research, overseeing commercial
development of the CLINAC. He continued to consult
for Varian since then.

A fellow
of the American Physical Society, Brown was awarded
the 1989 Prize for Achievement in Accelerator Physics
and Technology by the U.S. Particle Accelerator
School, a postgraduate training venue for scientists.

"He
was a scientist and very much a 'people person,'
liked by so many," recalled Lüth. In his spare
time, he enjoyed reading nonfiction, science history
and world events.

A
longtime resident of Menlo Park, Calif., Brown is
survived by Lüth, as well as five children from his
earlier marriage to Anadel Smith-Law (Stanford Class
of 1947) ­ David Brown of Danville, Calif.;
Dennistoun Brown of Billings, Mont.; Adriana Cassani
of Lindon, Utah; Jeremy Brown of Los Altos, Calif.;
and Andrew Brown of Mountain View, Calif. -- and 14
grandchildren. Three of his children -- David,
Dennistoun and Jeremy -- are Stanford graduates.

A
memorial service will be held Sept. 27 at 10 a.m. at
Valley Presbyterian Church, 945 Portola Road, Portola
Valley. In lieu of flowers, the family prefers
contributions to the Karl L. Brown Memorial Young
Scholars Fund or written recollections of favorite
memories of Brown. For details, see
www.karlbrown.info.